The present invention relates to a mobile telephone system for automatically paging a called mobile subscriber through a pager upon reception of an incoming call to the mobile subscriber while he is absent.
Mobile telephone systems have been commercially available for connecting a ordinary or stationary subscriber telephone set to a mobile telephone unit installed in a motor vehicle. A typical example of a conventional mobile telephone unit is described in "Mobile Unit for 800 MHz Band Land Mobile Telephone System", Review of the Electrical Communication Laboratories, Volume 25, Number 11-12, November-December, 1977. In the conventional mobile telephone unit, when an incoming call is made to a mobile subscriber using a mobile telephone set and he is in or near the vehicle, he can respond to an audible ringing sound from the telephone set. However, while he is away from the vehicle, he carries a pager. Upon reception of an incoming call, a paging system is automatically started by a mobile telephone exchange to call the pager of the mobile subscriber. In this case, the mobile subscriber is informed of the reception of an incoming call and is told the telephone number of the calling stationary subscriber.
In order to automatically start the paging system, hardware such as a memory associated with a rerouting request for the pager, a dial pulse sending circuit for sending the pager number of a called party, and a DTMF oscillator must be mounted in a mobile telephone exchange. Alternatively, software can be changed. For this purpose, the existing mobile telephone exchange must be modified. In addition, although the calling stationary subscriber can call the pager, cumbersome operations are needed.